Exceptionally stable blue phosphorescent organic light-emitting diodes

Cyclometalated Spirobifluorene Imidazolylidene Platinum(II) Complexes with Predominant 3LC Emissive Character and High Photoluminescence Quantum Yields

“…Since most of the literature-known phosphorescent Pt­(II) complexes demonstrate mixed-ligand-centered (LC) π–π* and metal-to-ligand charge transfer character (MLCT), the population of d–d states poses a problem for the design of blue phosphorescent bidentate cyclometalated C^C* imidazolylidene Pt­(II) complexes . As a consequence, research efforts focused on tridentate − and tetradentate ,,− phosphorescent metal complexes with the aim to increase the rigidity of the ligand sphere of such complexes and prevent deformations in the excited state. Alternatively, employing ligands possessing large LC π–π* energy gaps and strong σ-donating NHC ligands could effectively avoid the population of undesired MC d–d states as well .…”

Tetradentate Pt(II) Complexes with Peripheral Hindrances for Highly Efficient Solution-Processed Blue Phosphorescent OLEDs

“…19 Devices of PtON7-dtb showed a pure-blue emission of CIE (0.148, 0.079) with a narrow FWHM of 29 nm and also achieved a high external quantum efficiency (EQE) of 24.8%. 20 Recently, Sun et al reported that blue PhOLEDs achieved superior electroluminescent (EL) efficiencies and stabilities, 21,22 shedding light on the ultimate problem-solving possibilities of blue PhOLEDs by tetradentate Pt(II) complexes.…”

Pure blue phosphorescent platinum(ii) emitters supported by NHC-based pincer type ligands with unitary emission quantum yields

“…1–5 While Pt( ii ) emitters have demonstrated highly competitive performances in the green 6–9 and red 10–12 spectral regions, examples of efficient blue Pt( ii ) emitters are scarce. In this endeavour, significant progress has been made over the past few years by the groups of Li, 13,14 Wang, 15 Che, 16 and others 17,18 who capitalized on the use of rigid tetradentate cyclometalated ligands to develop platinum( ii ) emitters that display high thermal stability and outstanding photoluminescence (PL) and electroluminescence (EL) performances. Nonetheless, the multistep synthesis of tetradentate cyclometalated ligands with mixed C and N donor atoms is a bottleneck that impedes the tailoring of emission characteristics through structural modification.…”